Evaluation of stray current from a DC-electrified railway with integrated electric-electromechanical modeling and traffic simulation

Leakage currents from a dc-electrified railway requires careful consideration throughout the life time of the railway. The design objective is to minimize the current leakage from the railway return path (the running rails for a dc-electrified railway, with possibly additional conductors in parallel for ac-electrified systems). For this objective to be met, the design needs to account for foreseeable misuse during the construction phase (i.e., the lack of independence between the earthing system and the stray current collection system, due to space and construction exigencies in a viaduct) and degradation of insulation due to ageing and poor maintenance. Perhaps, more importantly, other influences, such as the train characteristics, time tabling, headway, multiple train movement, etc., need consideration to determine the worst case leakage current and, thus, the ability to define appropriate mitigations with respect to stray current management. In this paper, we describe the implementation of an integrated model for the assessment of stray current for a dc-electrified railway, in which these factors are considered. We provide an analysis of the stray current magnitude under worst case train operating conditions (i.e., multiple trains with a 90-s headway accelerating) and highlight factors that determine the efficiency of the stray current collection system. The integrated model presented enables a detailed assessment of all factors impacting the stray current magnitude, as well as an assessment of the overall performance of the stray current collection system.